Sporicidal Activities of Disinfectants on Paenibacillus larvae.

Abstract

ABSTRACT. Sporicidal activities of glutaraldehyde, sodium hypochlorite, povidone iodine, ethylene oxide gas, chlorhexidine gluconate, and didecyl dimethylammonium chloride on wet and dry spores of Paenibacillus larvae (basonym: Bacillus larvae) were evaluated for control of honeybee American foulbrood. Glutaraldehyde was found to have a strong and rapid effect on both the wet and the dry spores among the disinfectants tested. -KEY WORDS: disinfectant, Paenibacillus larvae, sporicidal activity.J. Vet. Med. Sci. 59(10): 953-954, 1997 and mixed in J-agar for counting the colonies grown from the viable spores after 7-day incubation. The results were expressed as the means of 2 experiments. The Association of Official Analytical Chemists (AOAC) Handbook describes the preparation of dry spores for the standard method of sporicidal test, because the spores in nature are usually dried and adhere to other materials. For the present study, we prepared the dry spores according to the AOAC method [14]. Briefly, penicylinders (6 mm in diameter, 10 mm in length, Fisher Scientific Co., U.S.A.) of porcelain were soaked in the wet spore for 15 min, and subsequently dried in a vacuum desiccator at room temperature for 24 hr. The numbers of the dry spores adhering to the penicylinder were determined to be approximately 10 4 by counting the colonies grown from the spores resuspended in saline. The dry spores were dipped in the solution of disinfectants and incubated at room temperature without agitation. At different time of incubation, the samples were transferred to saline for counting the number of viable spores as described above. The results were expressed as the means of 5 experiments.In cases of the chlorhexidine gluconate and didecyl dimethylammonium chloride, the samples, the spores exposed to the disinfectants, were diluted sufficiently before mixing in J-agar for avoiding errors caused by the clumping of the spores [5]. In the case of EO gas, the dry spores were fumigated in a chamber (UDONO, Tokyo, Japan) at 60°C under 90% relative humidity.The sporicidal activities of disinfectants tested in this study are summarized in Fig. 1. The glutaral showed the most remarkable sporicidal activity on the spores of P. larvae, especially the dry spores were more susceptible than the wet spores. No viable spore was detected in the wet and the dry spores after exposure to 2% glutaral in 20 and 5 min, respectively. Similar results have already been described for B. anthracis and B. pumilis [13,15]. These results suggest that the concentrations of 2% or more of glutaral are recommended for the practical use.Similarly, the dry spores were more susceptible to NaOCl than the wet spores. No viable cell was detected in the dry spores after 40-min exposure to NaOCl at every concentrations tested, whereas many viable cells still remained in the wet spores at the concentrations below 0.0125% AvCl. On the basis of the data, NaOCl containing Paenibacillus larvae (basonym: Bacillus larvae) is the causative agent of American foulbrood (AFB), wh...

Disinfection of wooden structures contaminated with Paenibacillus larvae subsp. larvae spores

“…To corroborate our findings, we did an EST with bleach. We found that spores were effectively destroyed by concentrations corresponding with those found by Okayama et al . (1997).…”

“…These results seem to be somewhat con¯icting with those published by Okayama et al (1997). These authors found that low concentrations (0á05%) of sodium hypochlorite were suf®cient to destroy P. larvae subsp.…”

“…To corroborate our ®ndings, we did an EST with bleach. We found that spores were effectively destroyed by concentra-tions corresponding with those found by Okayama et al (1997). Without organic contamination a 0á3125°solution (» 0á1% NaOCl) resulted in a complete decontamination, whereas in the presence of 2% yeast extract a 5°(» 1á55% NaOCl) solution was required.…”

Virucides in apiculture: persistence of surrogate enterovirus under simulated field conditions

“…However, information concerning the use of iodophores in the area of beekeeping is scarce. Only a slow‐acting sporicidal effect of highly concentrated povidone‐iodine on Paenibacillus larvae spores has been described …”

“…Only a slow-acting sporicidal effect of highly concentrated povidone-iodine on Paenibacillus larvae spores has been described. 13 Seven of the eight most common viruses infecting Apis mellifera (reviewed by Manley et al 14 ) are members of order Picornavirales. 15,16 15 Physicochemical properties of both f. Iflaviridae and f. Dicistroviridae have not been fully established.…”